Signal transmitter



Oct. 16, 1951 E. VROOM 2,571,800

SIGNAL TRANSMITTER Filed Aug. 9, 1950 2 SHEETSSHEET 1 7 FIG.

//v VEN 706 E. VROOM ATTORNEY Oct. 16, 1951 E VROQM SIGNAL TRANSMITTER 2 SHEETS-SHEET 2 Filed Aug. 9, 1950 AT 7' ORNE V Patented Oct. 16, 1951 SIGNAL TRANSMITTER Edward Vroom, Ossining, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application August 9, 1950, Serial No. 178,459

This invention relates to a signaling system- Claims. (Cl. 177-380) and more particularly to a system for selectively generating and transmitting code pulses.

An object of this invention is the accurate and rapid transmission of signals.

Another object of this invention is the rapid translation of information into code pulses representing that information.

A feature of this invention is the use of multicathode gaseous discharge devices as code pulse generators.

Another feature of this invention is the use of a plurality of multicathode gaseous discharge devices operable selectively and cooperatively to transmit code ulses.

In general, the system utilizes multicathode gaseous discharge devices with each of those devices being arranged to operate in response to pulses applied thereto to advance the conductive path therein step by step from cathode to cathode. Selected ones of the cathodes of each of said devices are connected to a common output means. Means are provided selectively to energize said devices in accordance with the information to be transmitted whereby the selected devices cooperate to produce a series of code pulses representative of that information.

The invention may be more fully understood from the following detailed description of a preferred embodiment thereof when read with reference to the accompanying drawings in which:

Fig. l is an elevational view of a multicathode glow discharge device illustrative of one type of tube suitable for use in the present system;

Fig. 2 is a sectional view taken along 22 of Fig. 1 illustrating the arrangement of the several cathodes and the cooperative relation thereof with the anode, a portion of the anode being broken away to show certain of the cathodes more clearly; and

Fig. 3 is a circuit diagram representing a preferred embodiment of the invention.

The multicathode stepping tubes which are employed in the present system may be of any suitable type. A tube operable in a suitable manner is disclosed, for example, in the United States patent application of W. A. Townsend, Serial No. 101,322, filed June 25, 194.9, the disclosure of which is incorporated herein by reference. A representation of that tube is presented as Figs. 1 and 2 of the present disclosure.

In general, the disclosed gaseous discharge device comprises an anode and a plurality of cold cathodes in cooperative relationship with the anode, the cathodes being mounted in a row which may be rectilinear, circular or of other geometrical form. The cathodes, or certain of them, are electrically grouped and are so constructed and arranged that the discharge between one cathode and the anode may be stepped or shifted selectively to a path between the anode and another cathode in response to signal pulses,

the discharge shifting or advancing one position for each pulse.

Referring now to Figs. 1 and 2 of the drawings, the tube of the exemplary type comprises a plurality of cathodes I I, hereinafter referred to as A cathodes, and a second plurality of cathodes I2, hereinafter designated as B cathodes, all of the cathodes being mounted in a circular array with each A cathode II interposed between two B cathodes I2. The main anode I3 may be and is shown to be ring-shaped, and is supported in spaced relation with the A and B cathodes. An auxiliary, start, reset or normalizing electrode I4 is also provided.

In one method of operating the stepping tube, the start electrode I 4 is employed as a start anode cooperating with the electrode I5 which serves as a start cathode. A suitable positive potential is applied to the main anode I3, a potential negative relative to the main anode potential is appliedto the start cathode I5, and a potential positive with respect to the start cathode potential is applied to the start anode I4. A discharge initially occurs between the start anode I4 and the start cathode I5, with conduction then transferring so as to exist between the main anode i3 and the start cathode I5. If a negative pulse of suitable amplitude and duration then be applied to the B cathodes I2, the discharge will transfer initially so as to exist between the main anode and the first one of the B cathodes. This first B cathode is labeled IS in Fig. 2. At the cessation of the pulse, the discharge will transfer so as to exist between the main anode and the first one of the A cathodes in a counter-clockwise direction in the structure as shown in Fig. 2. This first A cathode is labeled I! in the structure as shown in Fig. 2 and is supplied with a suitable voltage through an impedance. In a similar manner, successive pulses applied to the B cathodes I2 will cause the conductive path in the tube to transfer so as to exist between the main anode I3 and the successive A cathodes: II. The directivity of the stepping is accomplished by the construction of the cathodes, in a manner fully set forth in the above-cited patent application or in any other suitable manner.

As the conductive path progresses step by step from position to position in the tube the conduction is limited to one path at a time, i. e., the conduction between the main anode and the previous A cathode H is extinguished. This may be accomplished by utilizing a suitable impedance in series with the main anode of the device whereby the increased voltage drop across this impedance, resulting from the transfer of conduction to a B cathode I2, is sufficient to cause the voltage between the main anode I3 and an A cathode i l to fall below the sustaining value.

A circuit embodying the principles of the invention is shown in Fig. 3 of the drawings. In this circuit, five multicathode stepping tubes 30! to 305 are provided. These tubes may be of the type shown in Figs. 1 and 2 having both a start anode and a start cathode. Thus, if that tube structure be employed, in tube 31'", anode 305 is shown in Fig. 2 as anode [3, the first B cathode BI is the correlative of cathode H5 in Fig. 2 and the other B cathodes i132 to B8 are shown as the cathodes l2 in Fig. 2, the first A cathode [AS is shown as cathode I! in Fig. 2 and the other A cathodes [A8, lAl, 1A2, A4, [A1, IAE and IAX are the correlatives of cathodes H in Fig. 2, the Start anode ISA is the correlative of electrode [4, and the start cathode ISC is shown as electrode IS in Fig. 2. Similarly, tubes 302 to 395 are provided with elec trodes similarly designated to those of tube 381 except for the appropriate change of the initial character in each designation.

The system is preferably arranged to transmit code pulses on the so-called two-out of-five basis in which each of the several digits is represented by a particular combination of two elements. Thus, in the present system, in a discrete interval of time five pulses may be transmitted, time-spaced one from the other. Only two such pulses are transmitted, however, to represent any one digit, the time-spacial relation of the two pulses to the beginning of the discrete interval being selected in accordance with the digit which is to be represented. For example, the digit 1 may be represented by transmitting the first and the second of the five pulses, the digit 2 may be represented by the first and the third of the five pulses and so on, with the other digits being represented by other unique combinations of two of the five pulses.

-For convenience, the five pulses may be labeled the Nos. 0, 1, 2, 4 and '7 pulses so that, for all digits except the digit 0, the combination of pulses to be employed may be determined by the process of addition as follows :1

Pulse D igit Numbers purposes of clarity, as the 0 tube, the "1 tube, the 2 tube, the 4 tube and the '7 tube, respectively. As will hereinafter be seen, each of the tubes Still to 385 is also operative to transmit a start pulse to mark the beginning of the discrete interval and a stop or end pulse to mark the termination of the individual discrete interval.

To set the apparatus in operation, key ST is closed whereby positive battery, which may supply, for example, a positive l35-volt potential, is connected to conductor M5 and through resistors 32! to 325 to the anodes 306 to 3l0, respectively, of tubes 39! to 365, respectively. The start cathodes [SC to 580 of tubes 30! to 305, respectively, are connected through individual resistors 326 to 338, respectively, to conductor 33! which is connected to negative battery which may supply, for example, a negative 48-volt potential. When a suitable positive potential is applied to the start anode iSA of the 0 tube Bill, for example, in a manner hereinafter to be described, a discharge will be initiated between the start anode ISA and the start cathode ISO, and this discharge will immediately transfer so as to exist between the main anode 366 and the start cathode ISC. Similiarly, if a suitable posi-- tive potential be applied to the start anode ZSA to A of any of the other tubes 302 to 305, a discharge will be initiated between that start anode and the associated start cathode ZSC to 55C and that discharge will immediately transfer so as to exist between the associated main anode 38? to BIG and the start cathode 280 to ESC.

The B cathodes of all of the stepping tubes 36! to 3&5 are connected in multiple to conductor 332, thence through the closed contacts of op erated key ST to negative pulse generator 333.

This generator may be of any well-known type arranged continuously to supply negative pulses of suitable amplitude and frequency. For example, the tube structure shown in Figs. 1 and 2 has been found properly to respond to pulses applied at a rate in excess of 8000 pulses per second.

When the low impedance negative pulse generator 333 applies the first pulse to the B cathodes of tube 38! after a discharge has been initiated in that tube, the conductive path will be transferred so as to exist between the main anode 305 and the first B cathode IB! of tube 381. As a result, due to the increased voltage drop across anode resistor 32!, the potential at the main anode 305 of tube 38! will drop to a point where the potential difference between the main anode 3G6 and the start cathode ISO is below the sustaining value, and that discharge path will thereby be extinguished. As the pulse attenuates, the discharge in tube 30! will again transfer so as to exist between the main anode 3136 and A cathode IAS. Cathode IAS is connected to negative battery via output conductor 334 and through an output means which may comprise the winding of the recording head of a magnetic recorder 335. The current flow in conductor 334 resulting from the including of cathode lAS in the conductive path through tube 3! (or from the including of any other one of the start A cathodes 2A5 to 5A8 in the conductive path through any other one of the tubes 302 to 365, respectively) constitutes the start pulse which marks the beginning of a discrete interval of time during which pulses representative of a single digit will As negative pulse generator 333 continues to apply pulses to the B cathodes of tube 30!, for example, the conductive path is successively stepped to B cathode [B2, to A cathode IAO, to B cathode IB3, to A cathode IAI, to B cathode IB4, to A cathode IAZ, to B cathode [B5, to A cathode |A4, to B cathode IBB, to A cathode IA'I, to B cathode IB'I, to A cathode IAE, to B cathode IE and to A cathode iAX where the discharge rests. A similar stepping occurs in any other tube 302 to 305 which has been rendered conductive by the application of a suitable potential to the start anodes 23A to SSA, respectively.

The five A cathodes in each tube succeeding the start pulse A cathodes IAS to AS, respectively, are successively labeled IAO to 5A0, IAI to 5Al, IA2 to 5A2, [A4 to 5A4 and IA'I to 5A1, i. e., these five cathodes in each tube are designated in accordance with the above-described twoout-of-five code symbolism. The one of these five A cathodes in each tube which corresponds to the tube designation is connected to the output conductor 334. Thus, A cathode lA0 in the 0 tube l, cathode 2Al in the I tube 302, cathode 3A2 in the 2 tube 303, cathode 4A4 in the 4 tube 304 and cathode 5A! in the '7 tube 305 are all connected to the output conductor 334. The other four of the five digit-designating A cathodes in each tube are connected to negative battery through individual impedances and via conductor 33!. For example, A cathodes iAl, IA2, [A4 and lAl are connected through the individual resistors 340 to 343 and conductor 33! to negative battery. The final A cathodes IAX to 5AX are also connected to conductor 33% through individual resistors. It will be noted that the stop or end cathodes IAE to 5AE in the several tubes 30l to 305 are also connected to the output conductor 334.

It will therefore be seen that if tube 30! is stepped, a pulse will be applied to the output conductor 334 when the conductive path includes cathode IAS whereby a start pulse will be transmitted, a pulse will be applied to the output con ductor 334 when the conductive path includes cathode IAO, and a pulse will be applied to the output conductor 334 when the conductive path in tube 3! includes cathode IAE whereby a stop or end pulse will be transmitted. Similarly, as any other one of the tubes 302 to 305 is stepped, a start pulse will be transmitted when the conductive path therein includes the associated A cathode 2AS to 5A8, a digit-designating pulse will be transmitted when the conductive path includes the corresponding enact the A cathodes 2Al, 3A2, 4A4, or 5A1 and a stop or end pulse will be transmitted when the conductive path includes the associated cathode 2AE to 5AE.

As was previously indicated, two pulses are transmitted to designate each digit. Consequently, two of the tubes 30I to 305 are discharged and stepped simultaneously. The selective and simultaneous actuation of any two of the five tubes 30! to 305 is accomplished by means of the key-set comprising keys K0 to K9. The potential on conductor 315 is reduced to an appropriate value by the voltage-divider action of resistors 350 and 35l and the resulting potential is applied via conductor 352 to the upper contacts of all of the keys K0 to K3. Each of these keys is connected to two of the five leads L0, Ll, L2, L4 and L1 through a pair of varistors V! to V20. These connections are arranged in accordance with the above-listed code systems, i. e., key K0 is connected to conductors L4 and L1, key

Kl is connected to conductors LEI and LI, key K2 is connected to conductors L0 and L2, and so on. Conductors L9 to L1 are also connected to the start anodes ISA to 58A, respectively, of the no, 1) ((2,!) (I4)! K7) respectively. Therefore, if key K0 be operated, the positive potential on conductor 352 is applied through that key, through varistors Vi and V2 and via conductors L4 and Ll to the start anodes 48A and 58A of the 4 and 7 tubes 304 and 305, respectively. These tubes will therefore undergo a discharge and will step through their cycles. Therefore, a start pulse will be transmitted, a first digit-designating pulse will be transmitted when the conductive path in the "4 tube 304 includes its cathode 4A4, a second digitdesignating pulse will be transmitted when the conductive path in the 7 tube 305 includes its cathode 5A1 and an end pulse will be transmitted when the conductive paths in the two tubes include cathodes 4AE and 5AE. This series of pulses will represent the digit 0. It may be noted that although both of the discharged tubes transmit start and end pulses, since the B cathodes of the tubes are connected to a common pulse source, the tubes are stepped simultaneously so that only one start pulse and only one end pulse will be transmitted per cycle of operation of the two tubes.

The operation of any other one of the keys K0 to K9 will operate the appropriate pair of the tubes 30! and 305 in a similar fashion to transmit pulses indicative of the selected digit. It will be seen that any number comprising any number of digit may be transmitted by successively operating the proper ones of the keys K0 to K9.

Varistors V1 to V2!) are unidirectional current conducting devices and'may be gas diodes, dry rectifiers, etc. These varistors are represented conventionally, i. e., they represent a low impedance to conventional current flow when the arrow sides thereof are at a positive potentialrelative to the other sides. The varistors VI to" V20 are provided to prevent the operation of any tubes other than the selected pair of tubes. By the nature of the connections to the conductors Ll to L1, were it not for the varistors VI to V20, all of the tubes 30| to 305 would, improperly, be operated upon the closure of any one of the keys K0 to K9.

It will be apparent that the code basi may be varied from that shown. For example, ten tubes may be provided with the several-keys K0 to K9 being individual to those tubes and with an appropriate two of the A cathodes in each tube, in addition to the start pulse cathode and the end pulse cathode, being connected to the output conductor whereby only one tube need be operated to transmit a representation of any onedigit.

It is to be understood that the above-described arrangements are but illustrative of the application of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

-1. In a communication system, a pulse source, a plurality of gaseous conduction devices each having a first electrode and a plurality of other electrodes, output means, means connecting selected ones of said other electrodes in each of said devices to said output means, and means for selectively initiating a discharge in said devices, each of said devices when discharged bemg responsive to pulses transmitted from said pulse source to advance the conductive path therethrough step by step so that said path exists between said first electrode and successive ones of said other electrodes.

2. In a communication system, a pulse source, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, means connecting said pulse source to said second plurality of cathode in each of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, and means for initiating a discharge in selected ones of said devices simultaneously, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes.

3. In a communication system, a pulse source,

a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, means connecting said pulse source to said second plurality of cathodes in each of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, a plurality of switches, a source of potential connected to said switches, and means connecting each of said switches to selected ones of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is applied to the ones of said devices connected thereto, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes.

4. In a communication system, a pulse source, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes, a second plurality of cathodes and a start electrode, means connecting said pulse source to said second plurality of cathodes in each of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, a plurality of switches, a source of potential connected to said switches, and means connecting each of said switches to the start electrodes in selected ones of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is simultaneously applied to the ones of said start electrodes connected thereto, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes.

5. In a communication system, a pulse source, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes,

a second plurality of cathodes and a start electrode, means connecting said pulse source to said second plurality of cathodes in each of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, a pluralityof switches, a source of potential connected to said switches, and means connecting each of said switches to two of said start electrodes, each of said switches being connected to the start electrodes in a different pair of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is simultaneously applied to the ones of said start electrodes connected thereto, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes,

6. In a communication system, a pulse source, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes, a second plurality of cathodes and a start electrode, means connecting said pulse source to said second plurality of cathodes in each of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, a plurality of switches, a source of potential connected tosaid switches, and means including a pair of unidirectional current conducting devices connecting each of said switches to two of said start electrodes, each of said switches being connected to the start electrodes in a different pair of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is simultaneously applied to the ones of said start electrodes connected thereto, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes.

7. In a communication system, a pulse source, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes, a second plurality of cathodes and a start electrode, switch means for connecting said pulse source to said second plurality of cathodes in each of said devices, a source of potential, switch means for connecting said source of potential to the anodes of all of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, a plurality of switches, means for connecting said source of potential to said plurality of switches, and means connecting each of said switches to two of said start electrodes, each of said switches being connected to the start electrodes in a difierent pair of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is simultaneously applied to the ones of said start electrodes connected thereto, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes.

8. In a communication system, a pulse source, a plurality of gaseous conduction devices each having a main anode, a first plurality of cathodes, a second plurality of cathodes, a start anode and a start cathode, means for applying a potential to all of said start cathodes, switch means for connecting said pulse source to said second plu rality of cathodes in each of said devices, a source of potential, switch means for connecting said source of potential to the main anodes of all of said devices, output means, means connecting selected ones of said first plurality of cathodes in each of said devices to said output means, a plurality of switches, means for connecting said source of potential to said plurality of switches, and means including a pair of unidirectional current conducting devices connecting each of said switches to two of said start anodes, each of said switches being connectedto the start anodes in a different pair of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is applied simultaneously to the ones of said start anodes connected thereto, each of said devices being responsive to the application of a discharge-initiating potential to the start anode thereof to undergo a discharge between the start anode and the start cathode thereof and thereafter immediately to undergo a transfer of discharge whereby said discharge exists between the start cathode and the main anode thereof and being thereafter responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said main anode and successive ones of said first plurality of cathodes.

9. In a communication system, a pulse source, a plurality of gaseous conduction devices each having an anode, a first plurality of cathodes and a second plurality of cathodes, means connecting said pulse source to said second plurality of cathodes in each of said devices, output means, means connecting a certain one of said first plurality of cathodes in each of said devices to said output means, means connecting a different one of said first plurality of cathodes in each of said devices to said output means, means connecting an additional one of said first plurality of cathodes in each of said devices to said output means, the said additional one of said first plurality of cathodes being diii'erent in each of said devices, and means for initiating a discharge in selected ones of said devices simultaneously, each of said devices when discharged being responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes.

10. In a communication system, a pulse source, a plurality of gaseous conduction devices each having a main anode, a first plurality of cathodes, a second plurality of cathodes, a start anode and a start cathode, means for applying a potential to all of said start cathodes, switch means for connecting said pulse source to said second plurality of cathodes in each of said devices, a source of potential, switch means for connecting said source of potential to the main anodes of all of said devices, output means, means connecting a certain one of said first plurality of cathodes in each of said devices to said output means, means connecting a different one of said first plurality of cathodes in each of said devices to said output means, means connecting an additional one of said first plurality of cathodes in each of said devices to said output means, the said additional one of said first plurality of cathodes being different in each of said devices, a plurality of switches, means for connecting said source of potential to said plurality of switches, and means including a pair of unidirectional current conducting devices connecting each of said switches to two of said start anodes, each of said switches being connected to the start anodes in a different pair of said devices whereby upon the selective operation of any of said switches a discharge-initiating potential is applied simutaneo-usly to the ones of said start anodes connected thereto, each of said devices being responsive to the application of the discharge-initiating potential to the start anode thereof to undergo 'a discharge between the start anode and the start cathode thereof and thereafter immediately to undergo a transfer of discharge whereby said discharge exists between the start cathode and the main anode thereof and being thereafter responsive to pulses transmitted from said pulse source to said second plurality of cathodes therein to advance the conductive path therethrough step by step so that said path exists between said main anode and successive ones of said first plurality of cathodes.

EDWARD VROOM.

No references cited. 

